The present invention relates to a method and apparatus for thermal processing of slurry.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
To ensure clarity, it is necessary to establish the definition of several important terms and expressions that will be used throughout this disclosure. The term “slurry” is used here in a generic sense and may refer to sewer sludge in general, or to partly dried sludge having a moisture content of less than or little more than 10% of water. Partly dried sludge typically contains 60% of inorganic material, about 30% of organic material, and about 10% of water. Of course, sludge of greater water content may be applicable here as well.
Disposal of slurry that has accumulated in industrial plants or sewage plants poses a problem because farmers or agriculturists use slurry less and less to fertilize fields. The reason is the content of organic toxic agents and heavy metals that pose a risk to health and may be passed on to plants and fruits that grow on the fields. It is clear that entry of these types of materials into the food chain must be prevented.
It would therefore be desirable and advantageous to address this problem and to obviate other prior art shortcomings.